Two Is Better Than One
by xTotallyxTroyellax
Summary: AU Crossover: When the NYPD hits record-breaking numbers for its number of cases solved, the LVPD recruits Castle and Beckett to help them out with their own numbers. Snickers, and eventually Caskett


**Hello friends! So, for those of you who don't know, one of my current obsessions is ABC's show Castle featuring Nathan Fillion and Stana Katic. I've been thinking about a way to combine my two favorite shows (Castle and CSI) for a while now when this idea seemed to pop into my head. This will be relatively AU, seeing as when I write a story I like my couples to work out the way I want them too. So Snickers fans, congrats to you once again, you will get lots and lots of Sara and Nick fluff. Caskett fans, give me some time and I promise I will make you happy as well. Hope everyone enjoys!**

**Oh! And or my fellow Snickers fans, I promise I have not forgotten about "Save the Best for Last". I am currently working on the next chapter and just needed to get this idea out before it completely disappeared. =)**

**Background? Um, I would like to think Castle season 2ish and since I really wanted Grissom and Warrick in this story, I'll go with CSI season 3 so Greg still works in the lab.**

**Disclaimer: I own nothing, otherwise Detective Demming would be nowhere in the 12****th**** precinct and Sara would have dumped Grissom long, LONG ago.**

"Sir?" Detective Kate Beckett sputtered at the sheet of paper now held loosely in her hand.

"Don't look so confused Detective," Captain Roy Montgomery stated, taking a seat in the chair beside Beckett's desk, normally reserved for the renowned mystery writer Richard Castle, Beckett's current shadow and also current thorn in her side.

"Las Vegas?"

Montgomery kept up his best poker face, much to Beckett's chagrin.

"Sir, I don't understand why you are sending me to Vegas," she attempted again.

Beckett watched as Montgomery shifted a bit in the writer's chair before shrugging his shoulders.

"The commissioner got hold of yours and Castle's numbers for the past year and he is impressed. Your team has solved more cases than any other police department across the United States."

If Beckett was surprised by the news, she didn't show it. She knew her team was good, though she hadn't known just how good they were.

"I'm flattered sir, but that still doesn't answer the question of why you are sending me to Vegas," Beckett stated clearly.

"Oh you won't be going alone," Montgomery began, " Castle will be going with you."

"Please tell me you're kidding."

Montgomery gave Beckett a look, which told her he was not in fact kidding.

"Why Castle, sir? Couldn't I go with Ryan or Esposito?" she asked, a pleading tone laced in her voice. Montgomery was quick to shake his head.

"The LVPD commissioner wants to see what your team is doing differently to produce such high numbers. The difference between last year's numbers and these numbers is Castle."

Beckett folded her arms over her chest, making sure to bite her tongue in order to prevent a.) the profanities circling in her head and b.) retorting back to her captain. Noticing that Beckett wasn't going to say anything, Montgomery continued.

"This is a good opportunity for us detective. When the commissioner is happy…"

"I know, you're happy," Beckett finished for him.

The two were quiet for a moment, taking in the sounds of the 12th precinct hard at work.

"When do we leave sir?"

Montgomery removed himself from Castle's chair, before pulling two plane tickets from his inside pocket and handing them over to Beckett.

"Noon," he exclaimed, causing the young homicide detective's eyes to widen.

"Noon?! But that's only four hours from now!" she argued, glancing at her father's watch that was nestled on her wrist.

"Then I guess you need to call Castle and then head home to start packing," Montgomery said with a smirk as he headed away from the aggravated Beckett's desk.

"But sir!"

Montgomery turned around and pointed a finger in the detective's direction.

"This is non-negotiable detective. Ryan and Esposito have already agreed to take your case load."

Beckett watched as Montgomery walked back to his office, before letting out a groan. She should consider the entire thing to be a huge compliment to her and her team, yet all she could think about was how much of a chore it was going to be to babysit Richard Castle. Despite his childish ways, he was able to think outside the box, and it was that very thinking that had helped her and her team solve as many cases as they had.

Montgomery was right. Castle was the major factor behind their higher numbers.

Her thoughts were interrupted by the sound of her cell phone vibrating.

"Beckett."

The sound of heavy breathing was heard on the other end causing Kate's face to contort into confusion.

"Beckett…," the voice began, very deeply," this is your father."

Beckett looked at the caller ID and rolled her eyes before responding to the person on the other end.

"What the hell are you doing Castle?"

"How did you know it was me?" the writer whined causing Becket to smile.

"I'm a detective Castle. It's wh-"

"Yeah, yeah, I know. It's what you do," Castle responded in a mock imitation of Beckett's voice. "You looked at the caller ID, didn't you?"

Beckett rolled her eyes.

"It's what it's there for Castle. Now what did you need?" Beckett questioned as she began to gather up the stuff from her desk.

"How do you feel about Nikki Heat going to a Star Wars convention in the next book?"

"You're joking, right?"

"Bad idea?" Castle asked.

"Stupid idea Castle. Who would read that?"

"The closet Star Wars fans. We could have Heat dress up in that hot little slave girl out-"

"Absolutely not Castle."

Castle's voice once again resumed its whiney nature.

"Why?"

Deciding to ignore him, Beckett decided to dive right into what was on her mind.

"You actually picked a very good time to call," Beckett began to which Castle quickly responded with, "Do we have a case?"

"Well," Kate said, "not quite. You will need to pack a bag though."

"I knew it," Rick stated.

"Knew what?"

"That you wanted me."

Beckett rolled her eyes for the second time during the conversation.

"In your dreams Castle."

"Trust me," he exclaimed, "you are."

"Are you going to let me tell you why you need to pack your bags, or are you just going to continue to annoy me with your over-sharing?"

There was a pause on the other end, giving the female the impression that the male on the other side was actually considering his options.

"Annoying you is a lot more fun, but go ahead and tell me why I need to pack."

"Montgomery is sending us to Vegas," Beckett began only to be interrupted by Castle again.

"We're getting hitched?!"

"Castle…," Kate practically growled causing the man on the other end to mutter an apology.

"The LVPD commissioner was impressed with our numbers this past year and wanted to see what we are doing differently to produce such high numbers. The captain is sending you and I there to assist them for a few days," Kate summarized.

"When do we leave?" Castle questioned.

"Noon today," Beckett provided.

"Sounds like you and I ought to get packing! Don't forget to pack something nice for the wedding, and something even nicer for the wedding night!"

Before Kate could utter a response, the phone call ended with a click. Grabbing her things, Kate Beckett practically stormed out of the precinct, thinking of ways to kill Castle and get away with it.

"Perhaps the LVPD could help with that…," Kate muttered to herself, allowing a small smirk to form on her face.

CASKETT-SNICKERS-CASKETT-SNICKERS-CASKETT-SNICKERS-CASKETT-SNICKERS-CASKETT

The LVPD building was busy as usual, with lab techs bustling about and CSIs and police openly discussing individual cases. As the sunlight began to stream through the windows, it was clear to many of the building's occupants that the shift was almost over for some, and just about to begin for others.

One of the groups that was about to conclude was the graveyard shift of CSIs headed by the well-known entomologist, Gilbert Grissom. The entire team, minus their fearless leader, was lounging in the break room chit-chatting back and forth.

"You're hovering," Sara Sidle directed at her husband of almost a year who was currently standing behind her chair.

"Can you blame me?" Nick Stokes asked, causing the brunette woman to roll her eyes.

"She's pregnant Nick, not dying," Catherine Willows stated, eliciting a loud "Thank You!" from Sara.

"It's my first kid Cath. I just don't want her straining herself."

"Sara Sidle straining herself?" Warrick Brown teased, given Sara's history of being a workaholic. Sara picked up a pen from the table and threw it in Warrick's direction, who ducked just in time causing the entire room to chuckle.

"Does someone want to tell me why Sara is throwing things around the room?"

Everyone turned to look at Grissom, who had entered just in time to see the action.

"Just a little teasing boss. Won't happen again," Warrick provided, before turning in Sara's direction and giving her a smile only to receive a glare in return.

"Speaking of which, how are you doing Sara?" Grissom questioned.

"Do I look like a porcelain doll to you people?" Sara exclaimed, gesturing a bit wildly with her hands. " I am three and a half months pregnant. I am perfectly fine!"

Nick placed a hand on her shoulder, only to have it swatted away by his now very annoyed wife.

"We just need to make sure you are alright. We all care about you and don't want you overworking our future niece or nephew," Catherine stated, the rest of the team nodding their agreement.

Sara let out a sigh before responding to Catherine's statement.

"I appreciate all of your concern, but I can take care of myself. If things start to go badly, I will confine myself to my house or paperwork."

Nick frowned, though he knew Sara well enough to know that she would not be convinced otherwise. She and Catherine were equally as stubborn, often reminding the men of the team why they should not fall in their bad graces.

"What did you call the meeting for Griss?" Nick asked, looking to change the subject before Sara snapped again.

"We will be having some guests joining us for the next few days," Grissom announced.

"Is guests just a fancy word for new recruits?" Catherine stated bluntly.

Grissom turned his attention to his assistant supervisor.

"New York's Police Department has been raking in some high numbers when it comes to amounts of cases solved. High enough numbers that the commissioner wants to bring them in so we can pick up a thing or two."

"I don't think we can refer to Mac's team as guests anymore. We've worked with them plenty of times!" Warrick commented, agreements quickly voiced from the rest of the team.

"I never said it was a team of CSIs," Grissom replied coolly, receiving questioning looks from his team members.

"If it's not CSIs, why are we having them visit?" Sara questioned.

"It's what the commissioner wants," Grissom stated, " And I am not one to argue with the commissioner's wishes or the director's wishes."

"Do our guests have names?" Nick asked.

Grissom peered down at the paper resting in his hands.

"Homicide detective Katherine Beckett and…"

Grissom's face contorted into confusion.

"What's with the face Griss?" Warrick commented.

"It says our other guest is a mystery writer named Richard Castle."

Both women of the graveyard shift's eyes widened at the name.

"Hold up, Richard Castle? As in THE Richard Castle?" Catherine sputtered.

"Have you hear of him?" Grissom directed at Catherine.

Catherine let out a snort before looking in Sara's direction.

"He's one of the most successful novelists of our time," Sara confirmed. " Haven't you ever heard of the Storm series?"

Upon the clueless looks from the male team members, Catherine took control of the conversation again.

"Gathering Storm? Storm Season? Storm Warning? Storm Fall?"

Once again the males in the room were silent, forcing Catherine to look at Sara again.

"Apparently our male co-workers have never heard of the term "reading"," she said, eliciting a chuckle from Sara.

"What is a homicide detective doing paired with a mystery writer?" Warrick questioned.

"Well, Brown, if you picked up a book every now and then, maybe you would know," Sara jested causing a glare to be returned in her direction.

"Alright then Castle experts," Warrick demanded, "why don't you tell us?"

Sara gave a smirk before turning so she could address the entire team.

"Castle's most recent best seller, Heat Wave, is about a savvy female detective and her team solving a murder with a journalist as a tag-along," Sara explained.

"Page 105," Catherine added as an afterthought, with a knowing look on her face directed at Sara.

"Don't even get me started," Sara replied.

" So he's her boyfriend?" Nick asked to which both Catherine and Sara shook their heads.

"If I had to guess, I would assume he's doing research for his novels," Sara concluded.

"Is that what the kids are calling it nowadays?" Warrick teased from across the room, earning him dirty looks from both the husband and wife across the way.

"Anyways," Grissom interrupted, raising his voice a bit to get his team back on track. " Detective Beckett and Mr. Castle will be arriving in Las Vegas a little after five tonight and one of us needs to be there to pick them up."

" Sara and I will do it, " Nick volunteered.

"Perfect, " Grissom stated as he quickly scribbled something on a sheet of paper before handing it to Sara. "Here's the flight information. I expect you all to welcome our guests with open arms when they are here for shift tonight."

The team nodded before all excusing themselves to the locker room so they could grab their stuff and head home. Sara and Nick were the last ones to leave.

"Murder-Mystery novels?" Nick asked to which Sara responded with a shrug of the shoulders.

"You didn't like the forensics journals, so Catherine suggested something else to keep me occupied," Sara explained earning an eye roll from Nick.

"When I meant something new, I didn't mean something that still involved the art of murder darlin'."

"Well," Sara began as Nick took her smaller hand into his own, " maybe you should have been more specific with your original directions."

Nick chuckled as he and Sara exited the building, hoping to get a bit of sleep before their guests arrived in Las Vegas.

**Reviews would be lovely. =)**

**Cait**


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